Here on Earth, the reason we don't fall off is because we have a friend called gravity that we should be very thankful for! Gravity is the force that is constantly pulling you and everything around you towards the center of the Earth. Even though you can't necessarily feel yourself being pulled, gravity is always happening. In fact, you’d definitely know if it ever stopped because you'd suddenly find yourself floating in the air! And you wouldn't be the only one floating – gravity doesn't just keep you tied to the Earth, but everything around you, too! That's why the trash you throw in the garbage can doesn’t just float back out, and why objects you place on a table stay there, instead of wandering back up into the air!
Further informationOne really special thing about gravity is that it can’t be “shielded” or “stopped.” Even a plane or bird that can stay up in the air by flying is not “stopping” gravity. Instead, these things that can fly are keeping themselves up in the air by special means (like by how air is directed around their wings). If, for example, a bird were to stop flapping its wings, gravity would immediately pull it back towards the ground!
The amount of gravity that we have on Earth is unique; the moon, for example, has far less gravity than the Earth, which is why astronauts in space who jump up will stay in the air for longer before they touch back down again!
Ask a grown-up to help you find some pictures or video on the Internet where you can see astronauts in outer-space. What are some of the things you notice that are different because of the amount of gravity?
Sources & links
Nebel, Bernard J. Ph.D. “Chapter 13 ”“ Gravity, Momentum, Vibrations, and Sound.” Nebel’s Elementary Education. Maryland: Nebel’s Press for Learning, 2001. 301-304. Cain, Fraser. “Gravity on the Moon.” Universe Today. 13 Feb. 2011 "gravity." Merriam-Webster Online Dictionary. 2010. Merriam-Webster Online. 13 Feb. 2011